In the figure above, line l is prarallel to line m. If x=35, what is the measure of ∠ADC?
Approach
We are given ∠BAD. The other angle of △ABD must be complementary.
m∠BDA=90°−m∠BAD35°=90°−∠BADm∠BAD=55°
A similar approach is used to find m∠BDC. Since l || m, BD is perpendicular to line m since is it perpendicular to line l. Therefore m∠BDC=55° since the two angles divided by DC must be complementary.
m∠ADC=55°+55°=110°